Understanding CNC Motion Control, And Three Commonly Types
Knowledge

Understanding CNC Motion Control, And Three Commonly Types

The first benefit offered by all forms of CNC machine tools is improved automation Because of the operator intervention related to producing workpieces can be reduced or eliminated.
Published: Jun 02, 2020
Understanding CNC Motion Control, And Three Commonly Types

Many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks. This benefit gives the CNC user several side benefits including reduced operator fatigue, fewer mistakes caused by operating error, and consistent and predictable machining time for each workpiece. Since the machine will be running under program control, the skill level required of the CNC operator is also reduced as compared to a machinist producing workpieces with conventional machine tools.

The Heart Of CNC: Motion Control

The most basic function of any CNC machine is automatic, precise, and consistent motion control. All forms of CNC equipment have two or more directions of motion, called axes. These axes can be precisely and automatically positioned along their lengths of travel.

Instead of causing motion by manually turning cranks and handwheels as is required on conventional machine tools, CNC machines allow motions to be actuated by servomotors under control of the CNC and guided by the part program. Generally speaking, the motion type such as, rapid, linear, and circular, the axes to move, the amount of motion, and the motion rate or means feed rate are programmable with almost all CNC machine tools.

A CNC command executed within the control, which commonly through a program tells the drive motor to rotate a precise number of times. The rotation of the drive motor in turn rotates the ballscrew. And the ballscrew drives the linear axis. A feedback device at the opposite end of the ballscrew allows the control to confirm that the commanded number of rotations has taken place.

Though a rather crude analogy, the same basic linear motion can be found on a common table vise. As you rotate the vise crank, you rotate a leadscrew that, in turn, drives the movable jaw on the vise. By comparison, a linear axis on a CNC machine tool is extremely precise. The number of revolutions of the axis drive motor precisely controls the amount of linear motion along the axis.

Directions Of Motion (Axes)

The CNC programmer must know the programmable motion directions (axes) available for the CNC machine tool. The axes' names will vary from one machine tool type to the next. They are always referred to with a letter address. Common axis names are X, Y, Z, U, V, and W for linear axes and A, B, and C for rotary axes.

As stated, programs are made up of commands, and commands are made up of words. Each word has a letter address and a numerical value. The letter address tells the control of the word type. CNC control manufacturers do vary with regard to how they determine word names (letter addresses) and their meanings. The beginning CNC programmer must reference the control of manu-facturer's programming manual to determine the word names and meanings. Here is a brief list of some of the word types and their common letter address specifications.

  • O - Program number (Used for program identification)
  • N - Sequence number (Used for line identification)
  • G - Preparatory function (See below)
  • X - X-axis designation
  • Y - Y-axis designation
  • Z - Z-axis designation
  • R - Radius designation
  • F - Feedrate designation
  • S - Spindle speed designation
  • H - Tool length offset designation
  • D - Tool radius offset designation
  • T - Tool Designation
  • M - Miscellaneous function

Rotary axis departures still require a letter address (usually A, B, or C) along with the endpoint for the motion. However, the endpoint for a rotary axis motion is specified in degrees (not inches or millimeters).

The Three Most Basic Motion Types

While your particular CNC machine may have more motion types which depending on your application, let's concentrate on the three most common types available on almost all forms of CNC equipment. After briefly introducing each type of motion, we'll show an example program that stresses the use of all three.

  • Rapid Motion (Also Called Positioning)
  • This motion type is used to command motion at the machine's fastest possible rate. It is used to minimize the non-productive time during the machining cycle. Common uses for rapid motion include positioning the tool to and from cutting positions, moving to clear clamps and other obstructions, and in general, any non-cutting motion during the program.

  • Straight Line Motion
  • This motion type allows the programmer to command perfectly straight line movements as discussed earlier during our discussion of linear interpolation. This motion type also allows the programmer to specify the motion rate (feed rate) to be used during the movement. Straight-line motion can be used any time a straight cutting movement is required, including when drilling, turning a straight diameter, face or taper, and when milling straight surfaces.

  • Circular Motion
  • This motion type causes the machine to make movements in the form of a circular path. As discussed earlier during our presentation of circular interpolation, this motion type is used to generate radii during machining. All feed rate related points made during our discussion of straight-line motion still apply.

If you want to receive more instant messages, please follow our Instagram, Facebook, Twitter accounts.

Published by Jun 02, 2020 Source :mmsonline Source :mmsonline Source :mmsonline

Further reading

You might also be interested in ...

Headline
Knowledge
What is an Oscilloscope?
An oscilloscope is a diagnostic instrument that graphs electrical signals. Whether it is a simple or complex product, it includes electronic components, and its design, verification, and the debugging process require an oscilloscope to analyze the many electrical signals that make the product wake up.
Headline
Knowledge
What is Heat-assisted Magnetic Technology?
Heat-Assisted Magnetic Recording (HAMR) is a technology that uses laser heat to first heat highly stable media to assist in the magnetic recording of data.
Headline
Knowledge
Key Components of Automotive Semiconductors: ECU, MCU and Sensor
The automotive semiconductor market continues to be optimistic. At present, the main automotive semiconductor chips include microcontrollers (MCU), power management ICs, digital signal controllers (DSP), sensors, power semiconductors, discrete components, micro-electromechanical (MEMS), memory, customized application IC (ASIC), etc. The automotive chip supply chain is complex and long. After the shortage storm in 2021, automakers began to shorten the semiconductor supply chain, hoping to shorten the long chain. Some automakers even have the idea of developing and designing automotive semiconductors by themselves.
Headline
Knowledge
What is Sheet Metal Processing?
"Sheet metal" in sheet metal processing refers to thin metal plates, which can be processed by stretching, stamping, bending, etc., and the thickness is usually less than 6mm. Common materials include iron plates (black steel SPHC, cold-rolled steel SPCC, galvanized steel SECC), hot-dip galvanized steel sheet SGCC), stainless steel (SUS304, SUS316), aluminum (AL5052), copper, etc. Sheet metal processing is different from other processing technologies. It includes many different steps, such as: laser cutting, NCT punching, cutting, folding, welding, riveting, etc. The specific products produced are usually support frames, equipment covers, internal parts and some functional objects, such as electronic control panels, medical equipment covers, airport automatic clearance machine covers or parts, snapshot cabinets, food processing equipment covers and parts.
Headline
Knowledge
What is an Industrial Cooler?
A cooler is a device used for cooling during the manufacturing process.
Headline
Knowledge
How to Choose a Suitable Uninterruptible Power Supply System?
Uninterruptible Power Supply (UPS) is a device that continuously provides backup AC power for electrical load devices and maintains the normal operation of electrical appliances when the power grid is abnormal. Uninterruptible power supply systems can be divided into online, offline, and line interactive. The power requirements of each field are different. How to choose a suitable one?
Headline
Knowledge
What is Anodizing?
Anodizing is a treatment used to enhance the surface properties of metals. It can improve the appearance, durability, conductivity or other properties of a metal surface and help protect it from wear and corrosion. In addition, it can also be used to make different shaped materials, such as rubber rings, pressure-type parts or trimming cutting tools. Therefore, anodizing is a common metalworking method.
Headline
Knowledge
What is A Punch? Punch Principle, Type, Material Introduction
Punching machine, also known as stamping machine, is a forming process technology. There are many types of it. Due to different structural principles, the price and processing effect will be different accordingly, but they all have something in common in terms of structural composition. With the rapid development of the stamping industry, competition in all walks of life is increasing, and it is applied to various industries, such as aerospace, education, auto parts, diving equipment and so on. The following will introduce the punch structure, type and material.
Headline
Knowledge
Introduction to the Different Types of Welding
Welding is a manufacturing process and technology that uses heat, high temperature or high pressure to join metal or other thermoplastic materials such as plastics. According to the state of the metal in the welding process and the characteristics of the process, the welding methods can be divided into three categories: welding, pressure welding and braze welding.
Headline
Knowledge
What is Worm Gear?
A worm gear is a gear consisting of a shaft with a helical thread that meshes with and drives the gear.
Headline
Knowledge
What is Chip Formation?
In the chip formation process, materials are cut through mechanical means by using tools like milling cutters, saws, and lathes. It is an integral part of the engineering of developing machines and cutting tools.
Headline
Knowledge
What Exactly is a Boring Machine?
A boring machine, device for producing smooth and accurate holes in a workpiece by enlarging existing holes with a bore. A single-point tool is attached to a rotating spindle within a boring head. They can dig through anything from hard rock, soft soil to sand.
Agree